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Much Of Last Year's Hay Needs Supplement

Much Of Last Year's Hay Needs Supplement

Forage testing project in Iowa shows 13% of samples below 50% total digestible nutrients and another 34% between 50% and 55% TDN.

Thanks to an excess of rainfall this past summer, many producers had difficulty getting hay made in a timely manner which resulted in over-mature forage. As forages mature, they decrease in both energy and protein, and over-mature forage can lead to long term negative consequences in the herd, according to Iowa State University Extension beef specialist Denise Schwab.

With this in mind, the Iowa Beef Center requested help and financial assistance from ISU's Leopold Center for Sustainable Agriculture, the Iowa Forage and Grassland Council, and the Southern Iowa Forage and Livestock Committee to initiate a forage testing project.

Preliminary results available from Iowa forage testing project

"As of mid-January, more than 400 samples had been submitted to Dairyland Labs as part of this project, with about 350 of those samples being conventional beef cow hay or corn stalks," says Schwab. "The test results are important to producers."

A quick look at the data shows that 13% of the samples were below 50% total digestible nutrients (TDN,) and another 34% were between 50% and 55% TDN.

"While many variables can affect the beef cow's nutrient requirements, the full feed of these hays would be considered 'marginal' to 'deficient' in meeting the needs of the average pregnant beef cow during the winter months," Schwab says. "Another method of looking at forage quality is based on Relative Feed Value (RFV), with 100 being equivalent to full bloom alfalfa hay. Of the hays tested, 78% were below 100 RFV meaning there's a need for energy supplementation in those diets."

What do these hay testing results mean to the cattle producer?

At the very least, Schwab explains, conventional hay feeding programs may not be providing the required nutrients for late gestation cows, meaning some form of energy supplementation is required.

"If your forages haven't been tested for nutrient content, it's critical that you closely monitor the body condition of your cows. Ideally, each cow would have a body condition score of 6 at calving time to improve the likelihood of her cycling and rebreeding for next year," says Schwab. "Keep in mind that first cutting hay made in June is likely to be deficient in energy for the gestating beef cow and likely would need significant supplementation."

If you have questions on winter feeding of the beef cow or are interested in having your forages tested, contact your ISU Extension beef program specialist. Find your specialist at

IBC was established in 1996 with the goal of supporting the growth and vitality of the state's beef cattle industry. It comprises faculty and staff from ISU Extension, College of Agriculture and the ISU College of Veterinary Medicine, and works to develop and deliver the latest research-based information regarding the beef cattle industry. For more information about IBC, visit www.iowabeefcenter.

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